Stabilizing when at site

A few years ago many TT's came without the Mor/ryde system for TT handling and towing. Most today have some sort of this system.
One our first 35' I added this system and was rewarded with the better handling but notice the same complaints you have. To correct this I added a scissor jack on each side as close to the tires as I could. This has helped a lot.
On our 40' TT I have done the same thing and am quite happy with the results. We normally don't employ the center jacks for an over nighter but for the long term they are wonderful.
Hope this help. I have no less than 8 years on this concept and am happy.

I have a 29 foot that moves a lot. Even my 2 year old walking around is enough to shake the trailer. I don't have a solution yet. I borrowed X-Chocks to try. I could see the tires moved less with them on, but I still felt it shaking inside.

If you don't want to go the expense of the X-Chocks.

4" x 4" pressure treated, a length of 3/4" black or galvanized pipe & a 3/4" pipe clamp from Harbor Freight. Total cost of about $15

Some people have made themselves wood block wheel chocks that tighten between the tires. Cost - a few $$ compared to the X-Chocks.

You have electric stabilizers? Ours are Lipperts and I find they allow side to side rocking of our trailer, more so than our old hybrid with individual manual stabilizers. I'm going to try adding scissor jacks mid-frame.

But it will never be rock solid no matter what you do.

First, be sure your stabilizers are working and bearing weight. If they are and the wheels are well chocked it's about as good as it's going to get. Bracing the wheels together may help a bit but from what I've heard it's not going to change your life.

For comparison sake, I can feel it in the front when my kids in the rear bunks roll over. These things just aren't super stable.